US guidelines for nuclear-emergency evacuations

The government has recommended that all Americans within 50 miles of the damaged Japanese nuclear plant evacuate, saying it is what would happen in the U.S. if disaster struck. The Japanese government has told its citizens within 12 miles to evacuate. Here is how the U.S. protects its citizens in a nuclear emergency:

--The Nuclear Regulatory Commission requires each commercial nuclear reactor to plan for a 10-mile evacuation and sheltering area around the plant. That area is where the radiation plume is likely to come into direct contact with people.

--In addition, the NRC requires nuclear power producers to plan for a 50-mile area where consumption of food, water and milk would be banned. That's because at that distance, ingestion is the primary way people would be exposed to radiation.

While these two zones are required, they can be altered when conditions exceed the Environmental Protection Agency's Protective Action Guidelines (PAGs). EPA's PAG for evacuation states that evacuation of the public should occur when the projected dose to an individual is 1 rem, or about the dose from a full-body CT scan.